Posts Tagged ‘mass extinctions’

Elizabeth Kolbert has written a most unusual book. She has described the current mass extinction, known as the the Holocene extinction, or the Anthropocene extinction, or the Sixth Extinction. comparing it with the previous mass extinctions, of which 5 are famously massive. The cause varies – in each case something major and global occurred and changed the world: glaciation at the end of the Ordovician, global warming and changes in ocean chemistry at the end of the Permian, an asteroid terminating the Cretaceous. The cause of the current mass extinction is us.

Elizabeth Kolbert and her new book (salon.com)

Kolbert writes lucidly and with good humor about the history of the idea of catastrophic evolutionary change, including the resistance by many (including Darwin) to that idea despite the overwhelming evidence. Over the past 200 years, that evidence has become increasingly strong and detailed, combining detailed excavations of fossil beds, reconstruction of the chemistry of past atmospheres and oceans, and an understanding of continental drift forever forcing continents together and ripping them apart again.

Five mass extinctions have been identified in the fossil record. Each one changed the world.(washingtonpost.com)

Mass extinctions have been defined in different ways, but one of them is that 75% of existing species must be lost in a relatively brief geological time. Since we obviously haven’t lost that many species yet, are we really in a the midst of a mass extinction? The data are sobering: at the current rate of species achieving endangered, threatened or extinct status, we will hit that 75% mark with a couple of thousand years if not a lot sooner. That is an extremely brief geological time. We are well into what can only be called mass extinction if we don’t change course.

Species of birds, mammals, reptiles, amphibians, insects, corals and plants are becoming endangered or lost at a rate typical of a mass extinction (nature.com)

The current loss of marine species is harder to document than the loss of terrestrial species, but fisheries have collapsed from overfishing, coastal ecosystems have been radically altered by human development and pollution, ocean acidification now threatens oceans globally, and coral reefs have little future. The loss is everywhere.

Wooly rhinos, along with many other very larges species mammals and birds were hunted to extinction (angelfire.com)

All of this is well accepted fact, and Kolbert tells the story well. Only at the very end of the book do her conclusions emerge. They are, to say the very least, not optimistic.

She proposes that we are causing the current extinction not with malevolent intent, but because we are genetically driven: “With the capacity to represent the world in signs and symbols comes the capacity to change it, which, as it happens, is also the capacity to destroy it…Indeed this capacity is probably indistinguishable from the qualities that made us human to begin with: our restlessness, our creativity, our ability to cooperate, to solve problems and complete complicated tasks.”

Neanderthals did not coexist with us for long, though long enough that we carry a few of their genes (ornl.gov)

And there Kolbert ends her book. It deserves to be the best-seller that it is, but I do wonder if people are really reading her last chapter. It is a very cold bath.

So let’s continue past her ending. Can we change ourselves sufficiently to sustain reasonable biodiversity that let’s us all live on a livable planet? I think so. I have to think so.

We are way over-populated now, but a stable and even declining global human population lies not far ahead. That will help.

We can also, now, thoroughly protect very large ecosystems – like the Arctic and Antarctic, Canada’s Boreal forest, the Amazon basin, north and south cold-temperate coasts – along with many smaller ecosystems. That will help.

We can continue to educate the people of the world so that the seriousness of the the issues is truly recognized. Given knowledge, we are not stupid. Ignorance is treatable.

We can continue to press for more alternative fuels, reduced burning of fossil fuels and and lower emission rates of greenhouse gases: even the oil companies are prepared for Carbon taxes, if only they were forced to comply.

Our destructive dark side – war, poverty, greed, corruption and all the rest – can seem to be overwhelming, but we can continue to struggle to learn ways to diminish and suppress them, as we have done with slavery and racism: we know they need not dominate our various cultures. Velvet revolutions and true cooperation are not just dreams.

Our greatest challenge of course is ultimately time. We may not have enough of it. We may still slip over the edge into the bleakest of futures that won’t even include us.

But that is not inevitable, and we are more than the product of our genes.